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 Two cases of RBD raise the question of what is sleep for 
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Joined: Fri Aug 11, 2006 1:46 pm
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Location: SF Bay Area (Northern CA)
Post Two cases of RBD raise the question of what is sleep for
RBD (REM sleep behavior disorder) is common in LBD. (In RBD, dreams are acted out.) This is a short article about RBD in two Italian patients with MSA. (MSA is similar to LBD but there's no dementia involved.) One of the American researchers mentioned in the article believes that the definition of sleep must change, based on studies of these patients.
Robin


http://www.economist.com/science/displa ... d=12253173

Sleep
Restless

Sep 18th 2008
From The Economist print edition

A strange case raises the question of what sleep is for

THE function of sleep, according to one school of thought, is to consolidate memory. Yet two Italians have no problems with their memory even though they never sleep. The woman and man, both in their 50s, are in the early stages of a neurodegenerative disease called multiple system atrophy. Their cases raise questions about the purpose of sleep.

Healthy people rotate between three states of vigilance: wakefulness, rapid eye-movement (REM) sleep and non-REM sleep. But all three are mixed together in the Italian patients. The pair were initially diagnosed by Roberto Vetrugno of the University of Bologna and his colleagues as suffering from REM behavioural disorder, in which the paralysis, or cataplexy, that normally prevents sleeping people from acting out their dreams is lost. This can cause people in REM sleep to twitch and groan, sometimes flailing about and injuring their bedmates. These patients, however, soon progressed from this state to an even odder one, according to a report in Sleep Medicine.

One of the principal ways to measure sleep is to monitor brainwave activity, which can be done by placing electrodes on the scalp in a technique known as electroencephalography (EEG). Non-REM sleep itself is divided into four stages defined purely by EEG patterns; the first two are collectively described as light sleep and the last two as deep or slow-wave sleep. When the Italian patients appeared to be asleep, their EEGs suggested that their brains were either simultaneously awake, in REM sleep and non-REM sleep, or switching rapidly between the three. Yet when subjected to a battery of neuropsychological tests, they showed no intellectual decline.

Mark Mahowald of the University of Minnesota Medical School, whose group first described REM behavioural disorder in 1986, thinks memory consolidation is still going on in the brains of the two Italian patients; hence their lack of cognitive impairment or dementia. What needs to be revised in light of their cases, he says, is the definition of sleep.

Dr Mahowald suspects that sleep can occur in the absence of the markers that currently define it, which means those markers are insufficient. What’s more, the Italian cases lend support to an idea that has been gathering steam in recent years: that wakefulness and sleep are not mutually exclusive. In other words, the human brain can be awake and asleep at the same time.

That evidence takes the form of a growing list of conditions in which wakefulness, REM and non-REM sleep appear to be mixed. An example is narcolepsy, in which emotionally laden events trigger sudden cataplexy. When the dreaming element of REM intrudes into wakefulness, which can happen with sleep-deprivation, the result is wakeful dreaming or hallucinations. Since such dreams can be highly compelling, Dr Mahowald thinks they might account for some reports of alien abduction.

But there is another possible explanation of the Italian puzzle: that sleep is not necessary for memory after all. Jerry Siegel of the University of California, Los Angeles, has studied the sleep habits of many animals and thinks that could well be the explanation. All of which gives researchers something new to keep them awake at night.


Sat Oct 11, 2008 12:26 am
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Joined: Tue Feb 06, 2007 8:35 pm
Posts: 51
Location: Toronto, Canada
Post Sleep is beneficial to DNA repair mechanism
According to many cell biologists (Dr. Robert Roy et al., Concordia University, Montréal), healthy sleep serves to keep our immune system and DNA repair mechanism functionally optimally.

For the previous 20 years prior to mom's Dx, she took Sleep-Eze to aid her in sleeping after my dad had died of lung ca in 1986. We now know that the diphenhydramine in this OCT is countraindicated for those predisposed to LBD. I am not saying it was a causal factor as there is likely a web of causation involved in LBD, just a possible factor.

So many factors, it seems.

Blessings to all of you giving hands-on care.

:)

_________________
Dale
[My dear, Mom, Beatrice, (born in 1929) was diagnosed with LBD in Dec 2006. She passed away peacefully on July 12, 2013 at Embassy Hall, Shannex, Quispamsis, N.B.]


Sat Apr 11, 2009 1:17 am
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